Extracorporeal shock wave lithotripsy (ESWL) has become the preferred method of removal for the majority of symptomatic renal, ureteral, and biliary calculi. Recently, medical research has revealed that ESWL can cause a variety of acute and possibly chronic injuries. The propagation and focusing of shock waves in, and their interaction with, tissue and calculi is sufficiently complex that the aspects of the pressure field contributing to injury and to stone fragmentation cannot yet be identified. The main objective of the research is to gain fundamental knowledge of the properties of convergent shock wave in tissues, and their interaction with stone materials. A concomitant objective is to employ the knowledge so gained to assess the feasibility of developing instrumentation to both diagnose and control the lithotripsy process. Polyvinylidene fluoride pressure transducers will be used to acquire shock pressure and scattered wave data. The data will be used in conjunction with numerical shock dynamics calculations to understand the propagation process and in developing an empirical scattering model. It is anticipated that it will be possible to predict key elements of the interaction process by the use of innovative algorithms and to use the algorithms as a basis for new lithotripter instrumentation.